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2 years ago

An elevator is on the twentieth floor. It goes down 11 floors and then up five floors. What floor is the elevator on now?

Mathematics

1 answer:

love history [14]2 years ago

8 0

The answer is -4

because when you minus 11 and 20 that will get you -9 and then you add 5 that get you the answer

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astraxan [27]

The diameter in centimeters (cm) of a human hair is about 0.0025 cm. In terms of scientific notation, it is written as 2.5 x 10^-3 cm

7 0

3 years ago

Evaluate the surface integral S F · dS for the given vector field F and the oriented surface S. In other words, find the flux of

Tomtit [17]

Apparently my answer was unclear the first time?

The flux of F across S is given by the surface integral,

$\displaystyle\iint_S\mathbf F\cdot\mathrm d\mathbf S$

Parameterize S by the vector-valued function r(u, v) defined by

$\mathbf r(u,v)=7\cos u\sin v\,\mathbf i+7\sin u\sin v\,\mathbf j+7\cos v\,\mathbf k$

with 0 ≤ u ≤ π/2 and 0 ≤ v ≤ π/2. Then the surface element is

dS = n • dS

where n is the normal vector to the surface. Take it to be

$\mathbf n=\dfrac{\frac{\partial\mathbf r}{\partial v}\times\frac{\partial\mathbf r}{\partial u}}{\left\|\frac{\partial\mathbf r}{\partial v}\times\frac{\partial\mathbf r}{\partial u}\right\|}$

The surface element reduces to

$\mathrm d\mathbf S=\mathbf n\,\mathrm dS=\mathbf n\left\|\dfrac{\partial\mathbf r}{\partial u}\times\dfrac{\partial\mathbf r}{\partial v}\right\|\,\mathrm du\,\mathrm dv$

$\implies\mathbf n\,\mathrm dS=-49(\cos u\sin^2v\,\mathbf i+\sin u\sin^2v\,\mathbf j+\cos v\sin v\,\mathbf k)\,\mathrm du\,\mathrm dv$

so that it points toward the origin at any point on S.

Then the integral with respect to u and v is

$\displaystyle\iint_S\mathbf F\cdot\mathrm d\mathbf S=\int_0^{\pi/2}\int_0^{\pi/2}\mathbf F(x(u,v),y(u,v),z(u,v))\cdot\mathbf n\,\mathrm dS$

$=\displaystyle-49\int_0^{\pi/2}\int_0^{\pi/2}(7\cos u\sin v\,\mathbf i-7\cos v\,\mathbf j+7\sin u\sin v\,\mathbf )\cdot\mathbf n\,\mathrm dS$

$=-343\displaystyle\int_0^{\pi/2}\int_0^{\pi/2}\cos^2u\sin^3v\,\mathrm du\,\mathrm dv=\boxed{-\frac{343\pi}6}$

4 0

2 years ago

A right triangle has a height of 27 inches

ohaa [14]

Answer:

405 $inches^{2}$

Step-by-step explanation:

Area of a triangle = $\frac{1}{2}$ Base * Height

$\frac{1}{2}$ * 30* 27 = 405 $inches^{2}$

4 0

2 years ago

Read 2 more answers

ololo11 [35]

Answer:

A. 12

B. 26

Step-by-step explanation:

A. If the output is x = 3, then we just need to substitute 3 in place of x in the equation 2x + 6. This will give us a new equation, 2(3) + 6. 2 times 3 is 6, so we have 6 + 6 which is 12.

B. If the output is x = 10, then we just need to substitute 10 in place of x in the equation 2x + 6. This will give us a new equation, 2(10) + 6. 2 times 10 is 20, so we have 20 + 6 which is 26.

6 0

2 years ago

The difference between the solutions to the equation x squared = a is 30. What is a? Show that your answer is correct.

Trava [24]

You said that 'A is 30' right there in the equation
so it would be
Xsquared=30

5 0

2 years ago